1. Field of the Invention
The present invention relates to an apparatus and method for deciding an access system based on WLAN signal strength in a WLAN/mobile network interworking system, and in particular to an apparatus and method for deciding an access system based on WLAN signal strength in a WLAN/mobile network interworking system which can provide a roaming service by interworking a WLAN which provides a high speed wireless internet access service based on hot spots, and a mobile network which provides a national communication service.
2. Description of the Background Art
A WLAN is a system designed to provide a high speed wireless data service based on Ethernet. It has been used as a network solution in non-cabled places, such as factories, conference rooms and exhibition halls.
The WLAN serves to cut down network building expenses and improve business efficiency by supplying low-priced service equipment by partially restricting mobility of terminals, and thus application areas thereof have been gradually expanded. In addition, demands of users for the internet access have considerably increased and expanded into wireless sections due to huge distributions of a very high speed internet service. Thus, communication providers in the country or abroad attempt to provide the very high speed internet service by using the WLAN.
However, differently from a mobile network, the WLAN restricts mobility supports and thus fails to widely provide the service.
That is, the WLAN using 2.4 GHz band restricts outputs below 100 mW, and thus a service area of one access point exists within a 100 m-radius, which is clearly compared with a few hundreds m to a few Km of the mobile network. Accordingly, in order to obtain the same service coverage as the mobile network, the WLAN requires a lot of access points, which incurs large building expenses.
Moreover, the WLAN does not provide mobility functions such as diversity function, signal track function using fingers, and hand-off function as in the mobile network, and thus fails to flexibly support the internet service for a high speed mobile object.
Nevertheless, the WLAN is regarded as an important solution for providing the high speed wireless internet service because it can provide the high speed internet service at a low price in a specific area. Actually, demands for the high speed wireless internet access have been mostly generated in a fixed or walking state, specifically main business areas or public sections which a lot of general users crowd in.
Therefore, when the WLAN which provides the high speed wireless internet access service in a specific area and the mobile network which shows a low speed data rate but provides the internet access service regardless of places are interworked, namely when a communication provider provides the very high speed wireless data service by using the WLAN, the wireless internet access service can be efficiently provided by using the WLAN in the area where a lot of users demand the wireless data service, and the mobile network in the area where a small number of users demand the wireless data service. However, in order to use the WLAN to compensate for the wireless internet access service of the mobile network, a roaming service between the WLAN and the mobile network is necessary for service activation.
That is, a terminal must be provided with an access function to the mobile network and the WLAN, for using the WLAN service in the WLAN service area and the mobile network service in the other areas. Here, it should be determined whether to provide portability or roaming service for guaranteeing continuity of the service. When the terminal simply provides portability, the user may have to intercept the current service and select a wireless interface for re-access according to service areas. In the case that the terminal provides the roaming service, the wireless interface is automatically selected in order for the user to continuously use the service.
However, technical problems such as confirmation of service areas, roaming decisions, and access procedures between different wireless interfaces must be solved in advance so as to continuously and automatically provide the roaming service between the mobile network and the WLAN.